1991 Firebird Failed AZ Emissions Fuel Pressure Test
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Junior Member
Joined: Apr 2014
Posts: 37
Likes: 1
From: Phoenix, AZ
Car: 1991 Camaro RS, 1991 Firebird
Engine: None, 3.1l LH0 V6
Transmission: None, 700R4
Axle/Gears: 3.42 Open, 3.23 Open
1991 Firebird Failed AZ Emissions Fuel Pressure Test
I took the ol' Bird to get emissions tested and it failed all of the gas tests except for the NOx emissions test, and it failed the pressure test for when they test the fuel tank evaporative system. I have already changed out the catalytic converter for a Magnaflow direct-fit unit, but now I need to address the fuel pressure leak. I changed the gasket for the fuel tank back in August, so that's ruled out. The car also smells a bit like gas when you stand next to it, so it may very well be a pressure leak. Anybody have any suggestions as to what I should check next?
Joined: Sep 2000
Posts: 2,508
Likes: 197
From: Moorpark, CA
Car: '91 GTA, '92 T/A Convertible
Engine: GTA: 350 w/Vortec heads, T/A: 305
Transmission: Pro-built 700R4
Axle/Gears: GTA: 3.27, T/A: 2.73
Re: 1991 Firebird Failed AZ Emissions Fuel Pressure Test
Have you checked to see if that recall was complied with? Smelling fuel when filling up is an indicator.
Re: 1991 Firebird Failed AZ Emissions Fuel Pressure Test
I'm still going thru this myself.
Tank seal new, liquid weld where all hardlines go into the top of the sending unit for good measure, new solenoid on the evap canister, new wiring for said solenoid, no cracks can be seen in my hose. The only thing I have left to do is replace the fuel tank vent valve. I have already bought a rebuilt and tested unit from a member on here, just haven't installed it yet.
My car has had the recall done according to the dealership when I checked 14yrs ago. If that fuel tank vent valve doesn't do it, all that can be left is that the filler neck is to blame, no clue how I'm going to reach in there to put some liquid weld around that joint tho :/
Tank seal new, liquid weld where all hardlines go into the top of the sending unit for good measure, new solenoid on the evap canister, new wiring for said solenoid, no cracks can be seen in my hose. The only thing I have left to do is replace the fuel tank vent valve. I have already bought a rebuilt and tested unit from a member on here, just haven't installed it yet.
My car has had the recall done according to the dealership when I checked 14yrs ago. If that fuel tank vent valve doesn't do it, all that can be left is that the filler neck is to blame, no clue how I'm going to reach in there to put some liquid weld around that joint tho :/
Thread Starter
Junior Member
Joined: Apr 2014
Posts: 37
Likes: 1
From: Phoenix, AZ
Car: 1991 Camaro RS, 1991 Firebird
Engine: None, 3.1l LH0 V6
Transmission: None, 700R4
Axle/Gears: 3.42 Open, 3.23 Open
Re: 1991 Firebird Failed AZ Emissions Fuel Pressure Test
Funny you mention the filler neck, because the previous owner of my car hacked off the filler neck just to get the tank out, and used Quick Steel to stick it on. The seal they made broke, and was leaking the fuel. I guess I broke that seal after I changed the fuel pump and put the pump back in, and filled the tank up the other day. I bought a new filler neck, but now I need to affix it somehow.
I also robbed an evap canister off of my Camaro because the evap solenoid turned pretty damn hot after driving. I would take the fuel tank as well, but there's rust in the tank.
I also robbed an evap canister off of my Camaro because the evap solenoid turned pretty damn hot after driving. I would take the fuel tank as well, but there's rust in the tank.
Joined: May 2004
Posts: 2,262
Likes: 1
From: houston
Car: 83 POS monte carlo 2015 chevy P/U
Engine: 92 5.7 tpi 5.3
Transmission: 700r4 6L60E
Axle/Gears: 2.42 too high
Re: 1991 Firebird Failed AZ Emissions Fuel Pressure Test
a coupe of ways to fix this, replace the tank. pull the tank and take it & the neck to a radiator shop and have them repair it.
this isn't a factory fix and you may run into problems filling the tank, but maybe go to a wreaking yard and look for either pickups or vans, many have a rubber hose attaching the filler neck to the fuel tank. pick a hose that will fit snugly to your filler neck & use the hose & clamps to reattach your filler neck to the tank.
this isn't a factory fix and you may run into problems filling the tank, but maybe go to a wreaking yard and look for either pickups or vans, many have a rubber hose attaching the filler neck to the fuel tank. pick a hose that will fit snugly to your filler neck & use the hose & clamps to reattach your filler neck to the tank.
Thread Starter
Junior Member
Joined: Apr 2014
Posts: 37
Likes: 1
From: Phoenix, AZ
Car: 1991 Camaro RS, 1991 Firebird
Engine: None, 3.1l LH0 V6
Transmission: None, 700R4
Axle/Gears: 3.42 Open, 3.23 Open
Re: 1991 Firebird Failed AZ Emissions Fuel Pressure Test
UPDATE
Since my Firebird is a salvage title, I got it to pass inspection. I got tired of the stock seats, so I went Roadkill and drilled new holes to mount some bucket seats out of a Hyundai Tiburon. It was 30 bucks for both, and they have more support than the old ones.
I also ordered a new fuel tank from Summit Racing ($169 after all was said and done), and the car failed emissions. The car aced the carbon monoxide test, still failed the hydrocarbon test, and bombed the NOx emissions this time. I am pulling the tank out tonight to swap a fuel line that was too narrow for the fuel pump going to the sending unit, but is there anything else I should check?
Since my Firebird is a salvage title, I got it to pass inspection. I got tired of the stock seats, so I went Roadkill and drilled new holes to mount some bucket seats out of a Hyundai Tiburon. It was 30 bucks for both, and they have more support than the old ones.
I also ordered a new fuel tank from Summit Racing ($169 after all was said and done), and the car failed emissions. The car aced the carbon monoxide test, still failed the hydrocarbon test, and bombed the NOx emissions this time. I am pulling the tank out tonight to swap a fuel line that was too narrow for the fuel pump going to the sending unit, but is there anything else I should check?
Thread Starter
Junior Member
Joined: Apr 2014
Posts: 37
Likes: 1
From: Phoenix, AZ
Car: 1991 Camaro RS, 1991 Firebird
Engine: None, 3.1l LH0 V6
Transmission: None, 700R4
Axle/Gears: 3.42 Open, 3.23 Open
Re: 1991 Firebird Failed AZ Emissions Fuel Pressure Test
Here's a picture of those seats I put in.
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Thread Starter
Junior Member
Joined: Apr 2014
Posts: 37
Likes: 1
From: Phoenix, AZ
Car: 1991 Camaro RS, 1991 Firebird
Engine: None, 3.1l LH0 V6
Transmission: None, 700R4
Axle/Gears: 3.42 Open, 3.23 Open
Re: 1991 Firebird Failed AZ Emissions Fuel Pressure Test
Alright, so I went ahead and swapped the fuel line for the fuel pump on the sending unit. The car is running great now. I want to set timing on the thing just for good measure. In sum, the car has:
New fuel pump, filter, and tank
New fuel injectors
New intake plenum gasket
New EGR solenoid gasket
EVAP canister out of my parts Camaro
New catalytic converter
New distributor
New spark plug wires
Oddly enough, I haven't done the spark plugs yet. I am going to change them and get the thing an oil change while I'm at it. Is there anything else I should check before going back to emissions?
New fuel pump, filter, and tank
New fuel injectors
New intake plenum gasket
New EGR solenoid gasket
EVAP canister out of my parts Camaro
New catalytic converter
New distributor
New spark plug wires
Oddly enough, I haven't done the spark plugs yet. I am going to change them and get the thing an oil change while I'm at it. Is there anything else I should check before going back to emissions?
Thread Starter
Junior Member
Joined: Apr 2014
Posts: 37
Likes: 1
From: Phoenix, AZ
Car: 1991 Camaro RS, 1991 Firebird
Engine: None, 3.1l LH0 V6
Transmission: None, 700R4
Axle/Gears: 3.42 Open, 3.23 Open
Re: 1991 Firebird Failed AZ Emissions Fuel Pressure Test
Just as an update, I was able to get the car to finally pass emissions. I traced the issue back to some bad fuel injectors. I got a new set from SFI, and the car exceeded the emissions test by half of every figure. I want to thank everyone that helped with the troubleshooting!
Junior Member
Joined: Sep 2000
Posts: 48
Likes: 0
From: Phoenix, Az
Car: 91 Z28
Engine: 350ci TPI L98
Transmission: Stock 4L60
Re: 1991 Firebird Failed AZ Emissions Fuel Pressure Test
Did you ever diagnose what part of the evap system made you fail? Trying to get mine registered for the first time in Phoenix and car is passing everything except the evap pressure test.
Joined: Jun 2003
Posts: 5,028
Likes: 78
From: Desert
Car: 1991 Z28 Vert
Engine: 383 single plane efi
Transmission: T-56
Axle/Gears: 8.8 with 3.73s
Re: 1991 Firebird Failed AZ Emissions Fuel Pressure Test
I thought that phoenix allowed you to put collector/classic insurance on a vehicle and forego an emissions test? Are you wanting to use normal insurance and normal registration to daily drive it?
EDIT: I looked it up again, seems to have nothing to do with plates, just requires collector car insurance which is mileage limited. I'll be calling the DMV main office for the official policy as I will probably be moving to the Phoenix area in the next few years.
EDIT: I looked it up again, seems to have nothing to do with plates, just requires collector car insurance which is mileage limited. I'll be calling the DMV main office for the official policy as I will probably be moving to the Phoenix area in the next few years.
Last edited by Tibo; Mar 18, 2018 at 07:47 PM.
Junior Member
Joined: Sep 2000
Posts: 48
Likes: 0
From: Phoenix, Az
Car: 91 Z28
Engine: 350ci TPI L98
Transmission: Stock 4L60
Re: 1991 Firebird Failed AZ Emissions Fuel Pressure Test
For now it's back to being my daily transportation. That is something I need to look into for sure though once I get another car.
Joined: Jul 2000
Posts: 6,530
Likes: 94
From: Aridzona
Car: `86 SS / `87 SS
Engine: L69 w/ TPI on top / 305 4bbl
Transmission: `95 T56 \ `88 200-4R
Re: 1991 Firebird Failed AZ Emissions Fuel Pressure Test
The evap. line has rubber and steel, and runs from the tank to the engine bay.
Have a friend pressurize it, and spray soap bubbles along the whole length. Probably won't cost you much time. Shrink tubing will, in my experience, seal a pinhole underhood well enough to pass.
Keep at it.
Joined: Jun 2003
Posts: 5,028
Likes: 78
From: Desert
Car: 1991 Z28 Vert
Engine: 383 single plane efi
Transmission: T-56
Axle/Gears: 8.8 with 3.73s
Re: 1991 Firebird Failed AZ Emissions Fuel Pressure Test
If you pressurized the tank for that test, wouldn't the pressure escape through the pressure release valve/vent that comes off the tank?
Senior Member
Joined: Mar 2002
Posts: 998
Likes: 19
From: Ontario, California
Car: 1992 Z28
Engine: 383
Transmission: 700R4
Re: 1991 Firebird Failed AZ Emissions Fuel Pressure Test
The tank valve releases the pressure at 7lbs. The test is a low psi test. Only at 4 lbs.
Thread Starter
Junior Member
Joined: Apr 2014
Posts: 37
Likes: 1
From: Phoenix, AZ
Car: 1991 Camaro RS, 1991 Firebird
Engine: None, 3.1l LH0 V6
Transmission: None, 700R4
Axle/Gears: 3.42 Open, 3.23 Open
Re: 1991 Firebird Failed AZ Emissions Fuel Pressure Test
It's funny you ask at this time, because I had another evap problem. You really do have to check all the vacuum lines, because that held back my car from passing it's latest check.
I know the 3.1 and 2.8 V6 use an accessory vacuum pump, so you will want to check if you have a vacuum pump on the serpentine belt circuit. If the vacuum lines are toast in any way, the evap system won't work right. From there, just make sure that all vacuum lines are good, especially to the circular vacuum reservoir on the front left corner of the car under the battery, inside the fender.
Another culprit is the tank purge valve, which is the plastic thing that dangles next to the fuel lines. You carefully separate the two half of the valve and clean the springs and diaphragms inside the valve. They go back together pretty well.
Last things to check will be the charcoal canister, since the purge solenoid and another check valve go to the tank. If those are cracked, it is best to change them. And at the end, if all else fails, check the seal on the sending unit. I have messed with the likes of AZ emissions many times, and for our cars it gets annoying to check everything when you have panhard bars and intake cans in the way, but we are all here if you need to voice a few ideas off us if you make any discoveries on anything you find on your car.
I know the 3.1 and 2.8 V6 use an accessory vacuum pump, so you will want to check if you have a vacuum pump on the serpentine belt circuit. If the vacuum lines are toast in any way, the evap system won't work right. From there, just make sure that all vacuum lines are good, especially to the circular vacuum reservoir on the front left corner of the car under the battery, inside the fender.
Another culprit is the tank purge valve, which is the plastic thing that dangles next to the fuel lines. You carefully separate the two half of the valve and clean the springs and diaphragms inside the valve. They go back together pretty well.
Last things to check will be the charcoal canister, since the purge solenoid and another check valve go to the tank. If those are cracked, it is best to change them. And at the end, if all else fails, check the seal on the sending unit. I have messed with the likes of AZ emissions many times, and for our cars it gets annoying to check everything when you have panhard bars and intake cans in the way, but we are all here if you need to voice a few ideas off us if you make any discoveries on anything you find on your car.
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From: Chasing Electrons
Car: check
Engine: check
Transmission: check
Re: 1991 Firebird Failed AZ Emissions Fuel Pressure Test
The tank vent valve will vent out at 5.5 - 7.6 Kpa, which is between 0.8 and 1.1 psi. Note that this valves main purpose is to allow air into the tank as fuel is consumed.
In this role it opens at between 0.88" and 1.9" Hg of vacuum, which is between 0.43 and 0.93 psi.
If AZ is testing with 4 psi, the CCP system vapor control valve will open and relieve the pressure. Also, it seems that 4 psi into a large lightweight steel container (fuel tank), is a recipe for disaster. I did this once to leak check a tank. By the time it was at a few psi the tank started to balloon. Yes, I stopped right there and then.
RBob.
Member
Joined: Dec 2013
Posts: 175
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From: Scottsdale, AZ
Engine: 350-TPI
Transmission: 700-R4
Axle/Gears: 3.27 Posi
Re: 1991 Firebird Failed AZ Emissions Fuel Pressure Test
Senior Member
Joined: Mar 2002
Posts: 998
Likes: 19
From: Ontario, California
Car: 1992 Z28
Engine: 383
Transmission: 700R4
Re: 1991 Firebird Failed AZ Emissions Fuel Pressure Test
The filler neck and they pinch the line running into the canister during the test
Member
Joined: Dec 2013
Posts: 175
Likes: 1
From: Scottsdale, AZ
Engine: 350-TPI
Transmission: 700-R4
Axle/Gears: 3.27 Posi
Joined: Jul 2013
Posts: 1,208
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From: *member since 1999, I think - just can't remember my old name, and the big site crash...*
Car: 89 GTA ASC Conv., Prev: 89 GTA 6.3L
Engine: 5.7L L98 TPI
Transmission: 700r4 Automatic
Axle/Gears: 3.27:1 w/ JG1 Options:B2L, N10, U1A
Re: 1991 Firebird Failed AZ Emissions Fuel Pressure Test
So glad no more emissions tests on 1993-earlier vehicles where I live. 25 year rolling rule.
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Re: 1991 Firebird Failed AZ Emissions Fuel Pressure Test
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